This research is concerned with human oculomotor capacity and performance. Working thus far primarily with the contact lens optical lever technique and experienced committed subjects, we have been able to show that there is a slow control subsystem that humans can use to maintain the line of sight on stationary details even in the presence of moving backgrounds. We have also found that a similar system is present in the cat and can be activated by the monkey following special training procedures. Recently, we have begun to work with a Purkinje Image Tracker that can record eye movements in a 20 degrees field with a p-p noise level greater than 1 minute of arc. This instrumentation, coupled with a special purpose minicomputer, makes it possible to study naive subjects as well as ourselves because it requires no attachments to the eye and the computer makes it feasible to handle large volumes of eye movement data. We have also been working on the vestibulo-ocular response when displacements of the body are extremely small and slow (less than 10 minutes of arc with frequencies of arc as low as 0.1 Hz) and currently are trying to estimate the degree of retinal image motion produced by normal body movements.